Voltage peak at constant current boost converter when operating a switching on output side

Thread Starter


Joined May 5, 2020
Dear all,

when I use a buck/boost converter with a constant current setting like this one (LM2577S & LM2596S) and have a toggle switch with which I can choose between switching on one LED (LED1) or two LEDs (LED1+LED2), will there be a potentially damaging voltage peak when I switch from the two-LED array to the one-LED while the circuit is powered? Or is that danger not given due to the constant current of, say, 500 mA that is given off by the converter?

Here is a pic of the circuit, where the converter is represented by another fritzing part, but I guess you'll know what I mean.
Thanks and cheers,


Joined Mar 14, 2008
That circuit could potentially generate a voltage spike at the converter output if the switch is break-before-make (which most are).

f you wire the two LEDs in series and use a SPST switch to just short across the second LED that won't be a problem.